HEAT oven to 350ºF.
PREPARE cake batter as directed on package. Blend in drink mix; spoon into 24 lined muffin cups. Bake 20 to 25 min. or until toothpick inserted in centers comes out clean; cool completely. Meanwhile, spread 1 tsp. melted chocolate onto each graham square to completely cover top; place on baking sheet. Refrigerate until firm.
REMOVE liners from cupcakes; place cupcakes upside-down on plate. Use wooden spoon handle to poke deep hole in center of each cupcake. Spoon COOL WHIP into resealable plastic bag. Snip one corner from bottom of bag; pipe COOL WHIP into holes and onto tops of cupcakes, reserving small amount of COOL WHIP for later use. Top cupcakes with grahams, chocolate-sides up, to resemble graduation caps.
USE fruit rolls to make tassels for caps. (See Tip.) Add 1 tassel and jelly bean to top of each graham square, securing each with dab of remaining COOL WHIP. Keep refrigerated.